An in-vehicle or portable car navigation device is widely prevalent as a display device which shows a user geographic information. Moreover, in recent years, there is known a navigation device which displays a photographed image of an actual landscape taken by an in-vehicle camera and a navigation map image on a screen divided into two regions such as, for example, a right region and a left region, and which, when a user specifies either one of a structural object on the photographed image and a structural object on the map image on the screen, highlights the other structural object, so that the user is able to understand information around the user more intuitively (for example, refer to Patent Document 1 described below).